In the use of Internet services, the problem of user authentication or authentication of users frequently occurs. It is not presently possible to identify users of a service on the Internet in a secure manner. The recently introduced electronic identity card is a first step in this direction, but it requires the purchase of a read device for the NFC-based data transmission used. This purchase is not worthwhile if the customer wishes to use a service sporadically. Furthermore, the electronic identity card will not be globally available for some time.
In addition, it may be appropriate for a mobile operator not to identify a customer by name and address, but rather using the IMSI information allocated to the customer, i.e. the IMSI number (IMSI=International Mobile Subscriber Identification), since this is also used, where appropriate, as an identity feature in the billing systems.
Furthermore, a potential customer of an Internet service is always faced with the problem of allocation of usernames and passwords, insofar as the Internet service is to be able to be used again at a later time.
Insofar as a customer with a mobile terminal, i.e. a telecommunication terminal which comprises or contains an identity module, is registered in the telecommunication network of a mobile operator, it is easily possible for the mobile operator to identify the customer, since the mobile operator controls all network elements of the telecommunication network. The allocated IP address, for example, can thus be used as an identification feature.
However, if the mobile operator wishes to offer services outside its closed network (in order, for example, to keep security-critical components out of the inner core network, or to be able to offer a service not only to customers, but also to non-customers), the same problems occur which an external service provider also has.
Asymmetric cryptographic methods are known from the prior art, in which each of the communicating parties has a key pair which consists of a secret part (private key) and a non-secret part (public key). The public key allows anyone (i.e. a third party who knows the public key) to encrypt data for the owner of the private key. The private key allows its owner to decrypt data with the public key. The private key furthermore allows the owner to sign data, wherein a third party who knows the public key can check the signature generated in this way. For this purpose, the data are encrypted by the owner of the private key with the private key. The public key then allows the third party to verify the authenticity of these data signed (i.e. encrypted) with the private key by decrypting the data with the public key and comparing them with similarly transferred data in clear text. In contrast to a symmetric cryptographic method, the communicating parties do not have to know a common secret key.